I installed a newer version of the dd-wrt firmware and despite its pre-release status, it seems to work just fine. Port forwarding works (else you wouldn’t be reading this). And all the other features — like boosting the transmit power — are all there and working.
Now that I have successfully broken apart the webserving stuff from the household bandwidth usage, if the server needs to be rebuilt (it does) or craps out (it could), it won’t affect anything else.